Control system for electric motors.



C. G. TARKINGTON.

CONTROL SYSTEM FOR ELECTRIC MOTORS,

APPLICATION FILED MAY 9, 1911.

1,107,555. Patented Aug.18,1914.

VE TOR wedih i BY z z ATTORNEY '{INITED srn'r is PATENT OFFICE,

ILARENCE/G. ranxinorou, or CHICAGO,

ILLINOIS, ASSIGNQR T0 WEST NGHOUSE ELECTRIC AND MANUFACTURING COMPANY, AcoRroRA'noN' or PENNSYLVANIA.

CONTROL SYSTEM FOR ELECTRIC MOTORS, v

To all whom it ma' concern: H I

Be .it known t at I, C AR NCE G. 'TAR- iunorou, a citizen of theUnited States, and

a resident of Chicago, in the county of Cook and State of Illinois, have invented a new other apparatus, in which it is (esirable to automatically stop the motor'at predetermined limits and bring the driveninember to rest at. substantially the same point, irre- V spective of the load under which the motor is operated.

The object of my invention is to providea syst-enrof the characterabove indicated that shall be i?elati\ ely.-simple in arrm'igement andreliable in operation. I

W hena direct current motor has heretofore been employed for operating a skip hoist. and for similar purposes, a controller has been utilized to introduce a resistance in shunt circuit relation to the armature of the motor when the loaded car ncarly'rcached the limit of its ll'tOVBlI'lQflt path, in order to slow down the car without decreasing the torque of the motor and, consequently, to bring it to rest at the same point, irrespec- .tire of the load carried by it.

According to my present. invention, I utilize an alternating current motor in conjunction with a direct current generator of relatively small capacity which is operatively connected thereto, and I so varytlhe field strength and the load of the generatoras-to slowdown the motor and stop the car at the proper time. p

The single figure of the accompanying drawing is a diagrammatic view of a control system embodying my invention.

Referring to the drawing, alternating current energy is supplied from any suitable source to a motor 1, throughconductors 2, 3 and t, and electrically operated switches- 5, 6, 7, 8 and 9. The/motor is provided with external secondary resistance sections '10, 11 and 12, and a bralielil, adirect current gem erator 14, havingan armature 14, a series field windinglfi and a shunt field Winding pecificationof Letters Patent.

16 being operatively connected to the motor Patented Aug. 1.3, 191 4.

Application filed Kay 9, 1911. Serial No. 626,130v

by a' common shaft 17. The resistance-sections 10, 11 and 12 may be gradually short circuited byswitches 18 and '19 which are governed by a relay switch 20.

The generator may be loaded byg a resistance 21, controlled, by switches 22,23 and 24 which are governed by a relay switch-:25. The switches '5 to 9, inclusive, are governed by a master switch 26,"while the primary and secondary circuits of the'motor Land the circuits of the generator 14: may be governed automatically by means of ,a limit switch 27 when the car ofihe skip hoistor other driven member reaches predetermined points inns-movementpath ineither direction. i

The in." ier switch 26 is adapted to occupy either of t'sopositious X and Y 'and.:the

limit switch 27 cmnprises a movable. con

positions (I and I). as It e car approaches the opposite limit of such path.

- A ssunnug that the master-switch occupies its intermediate off position and that the linntswitch occupies position b, if 'the mas tact-bearing member 9S which occupiesz-ani ter switch is now thrown'to the positionY,

circuit connections will be establishedas fol- .lows: from lineconductor 4, througlrconductor 29, moving contact arm 30, Contact member 31, conductor. 32,

or the limit switch 1 whicharebridged by the contact member 34, conductor 35,

contact meinbers.

coils 36 and 37 of switches (land 8 and conductor 38 to line conductor 3. 'Switchesfi and S are consequently closedland-a circuit.

is established from conductor .29, through auxiliary switch 39,.which forms apartof switch 8, conductor 40, coil 4&1 of'switch 9 and conductor 38 toline conductor The I switch Dis thus closed as soon as the switches 6 and 8, which determinethe direction of motorrotat-ion, areclosed. 'Line conductor releases the brake,j is energiz since it it the engagement of contact member 47 with contact members 48 of the limit switch l-lowcver, as soon as thelimit switch o'ccu .pies position a, the reversal of the motor is under the control of the operator and may be governed by the master switch.

Assuming that the motor continues to rotate and that the limitswitch passes from position a into its intermediate position, a circuit is established from conductor 29, through contact arm 30 and contact member it) of the master switch, conductor 50, contact members 51, which are now bridged by contact member 52 of the limit switch, conductor 53, relay switch 20, which is closed as soon. as the first rush of current in the secondary circuit of the motor has subsided conductor 5%, coil 55 of switch 18, and conductor 56 to line conductor 3.

\V'hen coil 55 is energized, switch 18 is closed and portions of the resistance sections 10, ,11 and 12 are short circuited. The switch, when closed, is independent of the relay switch 20 since a holding circuit is established from conductor 53 through a resistance 53, an auxiliary switch 57, and the coil to conductor X "2. The sudden. increase in current in the secondary circuit of the mo tor will usually open the switch 20 temporalily and, when it is again closed, circuit is completed from conductor 54, through auxiliary switch 57, which forms a part of switch 18 coil 58 of switch 19 and conductor 56 to line conductor 3. The switch 19, when closed, completely short circuits the resistance sections 10, 11 and 12 and permits the'motor to operate at full speed. Sufiicientenergy cannot be supplied through the resistance 53 to close the switch 19 and it is therefore evident that .the'relay switch 20 will delay the action of the switch 19 and produce a gradual acceleration of the motor.

The shunt field 16 of the generator 14 is energized in the one or the other direction according to which of the switches 5 and is closed. Under the conditions above dc- -.;cribed, a circuit; is completed from terminal 59 of the generator armature, through conductor 1 60, auxiliary switch 61, which forms a part of switch 6, conductor-(2 shunt ficld 1G. conductor (33, auxiliary switch 64 of switch (3, and conductor (35 to armature ter animal (36. No load is applied to the generic tor, its armature circuitbeiiig interrupted except as it completed through a shunt lield, until the limit switch occupies position a.

it new assumed that the car of the ship hoist approaches the end of its movement path. the limit switch is so proper tioned as to move into position A circuit is established. through master switch 26 con-' ductor Contact members 33 of the limit switch, conductor 35, conductor 67, contact members which are brid 'ed by movable contact members 69. conductor 70, coil 71 of switch 22, conductor 72 and conductor 56 to line conductor The switch 22 is closed,

since coil 71 is energized, and a circuit is established from terminal of generator ll. through resistance 2]., switch 22 and. series field windin 15 to generator terminal 66. c

As soon as the,load is applied to the generator, as above indicated, the current traversing the motor circuit and the coil 43 of the relay switch 25 will be increased sufiiciently to open the relay switch and, as the motor is slowed down, this current will grin'lually be decreased until the relay switch isclosed. Circuit is then established from conductor 70, through relay switch 25, auxiliary switch 734 which forms a part of the switch 2 2, coil 74 of switch 23 and conductors 72 and 56to line conductor 3. The switch 23 is closed as soon as coil 74 is enersized and short circuits a portion of the re sistance 21, thereby increasing the load on the generator 14 and again causing the relay switch 25 to open. When the motor has been slowed down sufficiently. and the relay switch has again closed, switch 24 is permitted to close and the resistance 21 is still further;

reduced. The coils 7 1 of the switches 23 and 2; are rendered. independent of the relay sr-iitcli as soon as the switches are closed, circuits being completed from conductor 70, through auxiliary switches 75 and 76 in the usual manner. The speed of the motor is now very much reduced and the limit switch so proportioned that'its moving member The connection becomes into position d. tween contact members 33 is then broken and the line switches 6, S and 9 are opened. As soon as the supply of energy to the motor primary is discontinued, the brake magnet coil 15 is dci ncrgized and spring 46 sets the mechanical brake thereby bringing the motor to a standstill. The motor can only be rc-starlc in the opposite direction of rota tion. this action being accomplished; by throwing the master switch to positionX. The cycle of operation in the reverse direction is similar in allr spects, to that already described.

Variations in the arrangement and circuit con ections of the system may be effected Vi'lLlill the spirit and scope of my invention, and I desire that only such limitations shall ion the current be imposed as are indicated in the appended claims.

I claim as my invention:

1. A control system comprising a driven member, an alternating current driving motor connected thereto, a direct current genorator operatively connected to the motor and automatic means for establishing a load circuit for the generator, gradually decreasing the resistance of said circuit and inter rupting the'supply of energy to the alternating current motor at a predetermined lim't in themovement of the driven member.

2. A control system comprising an alternating current motor, a generator and a limit switch operatively connected thereto, and automatic means that is set in operation by the limit switch for successively establishing a load circuit for the generator and interrupting the motor circuit at predetermined limits of motor operation.

.3. A control system comprising a driven member, a motor operatively connected thereto, a generator, means forestablishing a generator load circuit and controlling the generator load, and means dependent upon traversing the motor circuit for automatically delaying the increase in the I generator load.

' .upon the limit 4. In a hoist controller, the combination with an alternating current driving motor. a generator opcratively connected thereto andra limit switch for establishing the generator circuit,of automatic means dependent circuit of the motor for reducing the resistance in the generator circuit.

5. In a control system, the combination with a driven member, an alternating current electric motor, a direct current genera-tor and a limit switch, the driven member, the generator and the moving element of the limit switch being opera-tively connected to the motor, of means dependent switch for completing a load circuit of the generator, and means dependent upon the current traversing the motor circuit for governing the generator load.

6. in a control system, the combination with an alternating, current supply circuit, a motor and independently operated switchcs'tor connecting the motor to the circuit and determining the direction of motor rotation, of a direct current generator operatively connected to the motor, means for completing a generator load circuit at predetermined limits in the operation of the motor.

upon the current traversing the primary 7. in a control system, the combination with an alternatiug'current supply circuit a motor and independently operated switches for connecting the motor to the circuit and determining the direction of motor rotation, of a direct currentgenerator operatively connected to the motor, means for completing a generator load circuit at predetermined limits in the operation of the motor, and means dependent upon the current traversing the motor circuitfor governing the generator load.

with an alternating current supply circuit, a motor and independently operated switches for connecting the motor to',the circuit and determining the direction of motor rotation, of a direct current generator operatively connected to the motor, of a.

8. In a control system, the combination limitswitch opcratively connected to the motorand adapted to successively connect a resistance across the urmutureof the generatoand interrupt the-motor circuit, and means de 'icndent upon the current traversing the motor circuitior delaying the action of the lust named means.

9. In a system of control, the combination with a poly/phase alternating current supply circuit, an induction motor having external secondary resistances and independently operated switches for connecting the motor to the circuit and determining the direction of motor rotation, of a direct current generator, a limit switch having a movable member operatively connected to the motor, a shunt field winding for the generator that dependent upon the reversing switches of the motor, a resistance for the generator arumiurc circuit that is dependent upon the limit switch, independently. oper-- ated switches for respectively short circuitinp; the secondary resistances of the motor and the armature resistance of the generator, menus dependent upon the current traversing the secondary circuit of the mo- CLARENCE G. TAR-K lNG-TON.

\Vitnesscs D. l3. llu'rcumson.

governing the generator 

